Unexpected "FocusDistanceUpper/lower" values in EXIF, when compared to similar image exif values.

[GuidoB]

I have few images that are flagged for several issues and one of them is this data point extracted from EXIF info. 

Ask: To check if such values are realistically possible from a canon camera (not interested in theoretical possibility), considering all 3 images, whose sample exif is shared below, are very similar and allegedly taken from a moving flight. 

Do you have any examples of images with such values, if yes, please share the image that already existed in the public domain. 

MakerNotes:FocusDistanceUpper	6.01 m
MakerNotes:FocusDistanceLower	1.55 m

[GuidoB]

I have with me some cr2s that were flagged and i'm in the process of reviewing them. One of them the data points that stands out are below. Can someone provide real world possibilities for such values, what kind of image would this be, and when would the camera set such values?. 

Camera is allegedly "Canon EOS 5D Mark II"

Lets call it Image_03, from which these values were pulled. 

MakerNotes:FocusDistanceUpper	6.01 m
MakerNotes:FocusDistanceLower	1.55 m

Here is EXIF of Image_01 and Image_02 with these values and lenses. All 3 images look similar with similar lighting. 

[johnrmoyer]

I also have the EF17-40mm f/4L USM lens. Since I regularly use exiftool to add the focus distance to web pages when I put photos on my web server, here are two that show similar focus distance values from the same lens (they were made on the same day at the same location with the same lighting):

https://www.rsok.com/~jrm/2023Feb14_birds_and_cats/2023feb013_thunderbird_IMG_3169c.html

https://www.rsok.com/~jrm/2023Feb14_birds_and_cats/2023feb013_thunderbird_IMG_3165c.html

The wayback machine did not archive those pages, but did archive the page with thumbnails: https://web.archive.org/web/20231202020737/http://www.rsok.com/~jrm/2023Feb14_birds_and_cats/index.h...

These photos are copyrighted and so are not public domain as you requested but do show similar focus distance numbers.

[GuidoB]

Hello Forum,

I have a set of images and when i extract the EXIF data using Exiftool, Online viewers like Exifmeta or Exifinfo.orgI see the order or sequence of metadata to be different.

The misalignment happens as shown in the attachment, Iin this set of say 10 images some share the order with the left/blue highlighted one, and some with the right orange highlighted one. 

Do you think the change in exif metadata sequence could be due to different Canon FW? Cse i'm using different exif readers and the misalignment is apparent. 

[johnrmoyer]

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@GuidoB wrote:

Hello Forum,

I have a set of images and when i extract the EXIF data using Exiftool, Online viewers like Exifmeta or Exifinfo.orgI see the order or sequence of metadata to be different.

The misalignment happens as shown in the attachment, Iin this set of say 10 images some share the order with the left/blue highlighted one, and some with the right orange highlighted one. 

Do you think the change in exif metadata sequence could be due to different Canon FW? Cse i'm using different exif readers and the misalignment is apparent. 

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The firmware version will be reported by exiftool in the Makernotes section. Exiftool also has options for dumping all of the meta data in hexidecimal with the location offset for where it is found in the file.

[Peter]

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@GuidoB wrote:

Do you think the change in exif metadata sequence could be due to different Canon FW? Cse i'm using different exif readers and the misalignment is apparent. 

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No. I checked my pictures. At least not without using verbose in Exiftool.

6D+50/1.4 USM vs 6D+17-40/4L USM

Firmware version

[Peter]

I owned 17-40. It reported sometimes Focus Distance Upper 6.01 m even when focused at infinity.

[GuidoB]

None that i have heard of, even called Canon support and their engineering team to check. Specifically, if the images are clouds with no visible obstruction, then the values are pretty easy to generate for a given lens. 

Is it a proof of manipulation? No, but one of our algos flagged it correctly as an anomaly. To remove the flag, i need real world proof that such a value is "expected". 

[Peter]

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@GuidoB wrote:

None that i have heard of, even called Canon support and their engineering team to check. Specifically, if the images are clouds with no visible obstruction, then the values are pretty easy to generate for a given lens. 

Is it a proof of manipulation? No, but one of our algos flagged it correctly as an anomaly. To remove the flag, i need real world proof that such a value is "expected". 

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Is the question still about the tags Focus Distance Upper and Focus Distance lower?

I sold my 17-40 many years ago. Reviewing my pictures taken with 17-40 I found that I was missing a lens profile for this lens, so I borrowed my friend's 17-40 and created a lens profile. At 35 mm it reported 6.01 instead of infinity (focused at clouds), so I had to redo the whole 35 mm set.

[GuidoB]

The values on your images make sense John. But when you get such values from similar looking cloud images from a flight, that's not acceptable optically speaking. 

Similar to how setting sun + cloud images have the following values- these values seem like they are taken from a different image and copied to cloud image with setting sun ( with sun not even visible in the image)

• EV value of 15
• Shutter speed 1/200 or 1/1000
• Aperture =8

You'd expect such values to come from a brightly lit images, but nope what we see is a dull orange tint clouds with one side slightly more orange due to setting sun. That's an optical anomaly. Mathematically yes the EV value for the shutter speed and Aperture makes sense, but once you know how to map these settings to the image, you know that's not expected.